In a morally weightless culture, moral grotesques run for public office, write books about themselves, give speeches, gab with Charlie Rose. Shame is as alien and unnatural as dentures.

If art is anything to go by—as it frequently is—sin is an outmoded hypothesis rotting on a beach somewhere, flotsam from a forgotten shipwreck. When was the last time you saw a serious depiction of that cautionary classic, the Seven Deadly Sins?

By the late ’60s, the heyday of pop art, sin was fast shedding whatever lingering frisson still clung to it. American painter and printmaker Ed Ruscha celebrated its obsolescence when he distilled the very concept of sin to a mere ribbon of a word. Stylish and tongue-in-cheek, his celebrated drawing “Sin” (1967) was prophetic in its way.

Pop sensibility worked its way into the bloodstream. Only a quarter-century later, the 1992 catechism of the Catholic Church dispensed with the seven deadlies in one scant paragraph (#1866) out of close to 3,000. In five lines plus a few syllables more, the dominion of those age-old designated enemies of virtue was given its due. Brevity pointed to the reign of mercy that is upon us now: “God has consigned all men to disobedience, that he may have mercy upon us all. (Rom. 11:32)”

Earlier ages—less sensitive, more astringent than our own—cautioned themselves against the progress of sin. Once upon a proverb, the seven capital sins were inscribed in Western culture by artists, poets, theologians, and homilists:

These six things doth the LORD hate; yea, seven are an abomination to him: a proud look, a lying tongue, hands that shed innocent blood, a heart that deviseth wicked schemes; feet that be swift in running to mischief, a false witness that speaketh lies, and he that soweth discord among brethren. (KJV)

Through the Middle Ages and into the Tridentine decades, many critical theological and confessional works were woven around the cardinal vices. In tandem with the Ten Commandments, they provided prevailing models for ethical inquiry and examination of conscience. Even into the mid-twentieth century, the loathly seven still hovered in modern imagination.

They have dwindled down to a precious few, these deadlies, and their names have changed. Now that our carbon footprint overrides the old roster, visual art is left empty-handed. The iconography of personal sin no longer applies. The vanity of flesh, the pandemonium of lust and hubris, the wrath of God—all gone now, part of an allegorical world steeped in discarded myth. With its absence, visual art has lost one of its most purposeful motifs.

Perhaps that is why I am so fond of vintage pulp fiction book covers. Had I the instincts of a collector, I would amass heaps of incunabula, medieval florilegia, and—I confess—trashy paperbacks from the 1940s into the early ’60s. Those 15 years after World War II were a publishing bonanza for short-order readers. The old dime novel, portable and ephemeral, mutated into the mass market paperback, so congenial to potboilers with racy cover illustrations.

I would rip the covers off my collection and arrange them, artfully matted and framed, across a wall dedicated to their brash, admonitory sleaze. You howl to object: “How could you? They are not beautiful!” Oh, but they are. In their downscale, streetwise, sometimes grisly way, they know debasement and corruption when they see it. There is beauty in that.

True, the graphics lack refinement. No soothing elegance softens the shabbiness of transgression. Grace of line and delicacy of hue are beside the point. Aesthetic refinement is as irrelevant here as in that picture Dorian Gray kept in his closet. All that matters is the judgment rendered. However much titillation accompanies it, judgment is inexorable. And unsmiling.

Mind you, I do not vouch for the prose. But those lurid covers upheld their own kind of discernment. They could tell the good guys from the bad. Take “G-Men’s” ace hero, Dan Fowler. He has character written all over his face. Between 1935 and 1953, he prevailed over public enemies and the racket-of-the-month. And he handled a gun in service to the law. Definitely a good guy.

Carrie, “daughter of sin,” tried to be good, honest she did. This 1951 cover is spot-on as an illustration of St. Paul’s lament in his epistle to the Galatians: “The flesh lustest against the spirit and and the spirit against the flesh, so that ye cannot do the things that ye would.” Within the set of vices that belong to us, some are more insistent than others. So sexual mischief ranks high between pulp fiction covers and on them.

Ignoble Layne made sexual bargains of all kinds to get ahead in the music and film industries. Alas, his infidelities brought on a lethal end. Was it AIDS before there was a name for it? Or did he run into the wrong guy?

Either way, in 1965 even gay porn acknowledged the ancient insight that promiscuity comes with consequences. They were born too soon, Layne and Carrie. Today they could down antibiotic cocktails or protease inhibitors while they checked the hook-up apps on their iPhones.

Mickey Spillane’s Mike Hammer tales, a take-no-prisoners series littered with mayhem, earn a wall all for themselves. They sold in the millions (close to 150 million by the early 1980s). “Kiss Me, Deadly,” published in 1952, became a film noir classic three years later.

One slice of dialogue is ageless: “There’s no such thing as innocence. Innocence touched with guilt is as good a deal as you can get.” That is as hardboiled a definition of original sin as you can get.

Among my favorites is Martin Abzug’s 1947 potboiler originally published under the title “Seventh Avenue Story.” Abzug was the stockbroker husband of the flamboyant Rep. Bella Abzug, feminist and activist extraordinaire in the 1960s and ’70s. Back then, girls like the blonde on the cover were called cheap. It was the worst thing a girl could be called. Now, I think, the word is liberated. And it is a compliment.

You know just by looking that this babe will come to a bad end. The spaghetti straps, the bangled dress slit to the hip—once it was the iconography of easy virtue. Now you might find it on any teenager. Maybe on your grandmother. But in 1963, it could still signal something raunchy, rough, or just no good. The back cover tells us that this “underage, over-sized” singer-on-the-make wore short shorts and her jerseys a size too small. How quaint that sounds.

The blurb is part come-on, part advisory against misdoing. Learn as she did that “the sweet smell of success didn’t come from a bed of roses.” Be warned that in a climb to the top, a gal might have “to spend a lot of time on the bottom.” Cheesy as it is, there is moral thinking at work in that double entendre. It is a warning, a veiled reminder that, in the last analysis, our souls are not our own. Established norms—the testimony of human tradition—have a claim on them.

“Harlot in Her Heart,” 1950.

Sex and wrath make the most appearances because they are the easiest to depict. Besides, popular culture is not much interested in the rest. It was not then; and it is not now. Only the packaging has changed.

Before you pull a fine French hem back from my affection for all this tawdry art, think for a bit on the latest episodes of Netflix’s sleek “House of Cards.” Skip past the betrayals and murders of earlier segments and stay with Frank Underwood (Kevin Spacey) as he pimps his wife Claire (Robin Wright) to her speechwriter.

“Why Get Married?” 1949.

In a straight-faced parody of Nietzche’s “beyond good and evil,” Frank and Claire decide to move “beyond marriage” to solidify their power. Frank suggests that his wife take the writer as a lover. The other man will give her what he no longer can, keep her warm at night, and ensure the quality of her speeches. Claire needs no encouragement.

Cut to the morning after. Frank is in the kitchen making toast. Claire and lover join him at the kitchen table. Frank passes the toast. All is cordial and civilized. Claire is regal. The décor is graceful, stylish. Nothing so shabby as sin could penetrate the refinement. The three occupy a private sphere exempt from the common morality of the vulgar masses.

The original buyers of my inelegant cheap reads shared a pre-existing framework. They inhabited a coherent tradition of expectation, faulty as it might have been, in which the possibility of making moral judgments was not yet tainted. The cover art had the virtue of acknowledging the centrality of sin even while exploiting it.

Maureen Mullarkey is an artist who writes on art and culture. She keeps the weblog Studio Matters. Follow her on Twitter, @mmletters.